Members of the RMT union are planning to strike on 1 and 4 September in a long-running row over driver-only-operated (DOO) trains.

The union has said it still has concerns over safety and job losses as a result of DOO operation, but Southern said changes in working practices were needed and it would make every attempt to minimise disruption.

'Congested network'

The automated compensation scheme, which has also been brought in on Gatwick Express journeys, uses algorithms to check for delays after a passenger taps in and taps out.

It sends an automatic claim to the passenger's online account, if there has been a delay, and GTR said passengers only needed to review the claim for accuracy and confirm the method of payment.

The automated system is complementary to the existing process, and people can still claim online or in writing.

Compensation used to be available for delays of half an hour, but Southern started paying out for delays of 15 minutes last December.

Passenger services director Angie Doll said: "Passengers have seen a significant improvement in Southern service levels but we still have more to do and when things go wrong on this, the most congested network in the UK, passengers deserve compensation."